The home XI scrambled through to 143/9 in their 45 overs, with Tim Gruijter's quality off-spin the pick of the Leeston-Southbridge bowlers, taking 3/19 off his nine overs.
Leeston-Southbridge also struggled to form partnerships in their chase, with Canterbury batsman Harry Chamberlain nicking off second ball to Sam Fleming who would end up with three wickets.
At 124/8 the match hung in the balance but it was New Zealand Army captain Dougald Munro who guided them home, with a composed 22 not out of 27 balls.
Sefton thumped Lincoln by 71 runs at Lincoln Domain after another fine knock by Amandep Arora.
Arora made 85 before he was run out, helping Sefton to post 221/9.
Canterbury Plunket Shield seamer Fraser Sheat took the new ball for Sefton and showed his quality, bagging five wickets, but doing most of his damage in mopping up the tail.
Lincoln opener Taylor Holland batted nicely for his aggressive 48 at the top of the order.
But after being 121/3 in the 26th over, and looking likely to chase down the target, Lincoln shuffled spectacularly, losing their final seven wickets for just 29 runs.
Southbrook suffered a humiliating nine wicket defeat at home to Ohoka.
On a difficult batting pitch, Austin Hamilton and George Mauger ripped through the Brook's top order before Hamish Williams and Rhys Mariu finished them off, rolling them for just 62.
Ohoka knocked off the meagre total in 12.3 overs for the loss of just Daniel Lyons.
Darfield had the bye, and in their final fixture Cheviot met Weedons.
Short scorecards:
• Oxford-Rangiora 143/9 (D Fulton 35, M Power 32; T Gruijters 3/19, S Chamberlain 2/19)
Lost to Leeston-Southbridge 144/8 (T Gruijters 31, D Munro 22no; S Fleming 3/38, J Sail 2/27, J Waghorn 2/28).
• Sefton 221/9 (A Arora 85, B Fleming 29, M Smith 21; A Gulati 2/29, E Paterson 2/50)
Beat Lincoln 150 (T Holland 48, L Robinson 23, J Suzana 21; F Sheat 5/33, T Waller 2/33, C Warner 2/36).
• Southbrook 62 (L Blom 20; G Mauger 3/10, R Mariu 2/5, A Hamilton 2/12, H Williams 2/13)
Lost to Ohoka 64/1 (R Mariu 34no).
